1. Field of the Invention
The invention generally relates to glass ceramic articles that are provided with patterned coatings. More particularly the invention relates to glass ceramic articles which have translucent features in coatings.
2. Background of the Invention
From the prior art, glass ceramic cooktops are known which are coated on the lower surface in order to modify the appearance and to conceal parts of the cooktop installed below the glass ceramic.
One option for this purpose are sol-gel coatings which are quite heat resistant and are distinguished by good adhesion to the glass ceramic plate. For concealing internal parts of a cooktop, opaque coatings are typically used.
For some applications it is desirable that the coating does not cover the entire surface but has windows. Such windows are in particular arranged in front of light emitting display elements, so that these display elements shine through the glass ceramic plate to be visible to an operator which looks at the utilization side of the cooktop. Partly, these windows are covered by translucent coatings to improve aesthetic appearance. With the same hue, a homogeneous surface is created in this manner.
Nowadays, icons, characters, or other logos and designs are printed on cooktops by screen printing. However, it is difficult to produce very fine patterns such as thin lines, for example.
Moreover, when very fine or small logos are to be produced the ink tends to smear, causing rejects. Furthermore, for every new product request or design change a new screen needs to be created, so that set-up costs are very high, which is especially noticeable in small series. Manufacturing of individual designs for each end user is therefore expensive.
Furthermore, for multilayer coatings in case of a printing technique such as screen printing the problem arises that congruent patterning is difficult. Therefore, in case of multilayer coatings usually a larger window is omitted, to allow to pattern a further coating layer with exactly the desired pattern in the area of the window. However, especially in combination with light emitting display elements the window might be visible if the more precisely patterned coating layer is not completely opaque.
EP 0 868 960 B1 discloses a process for manufacturing control panels, in particular for electrical household appliances, wherein at least one personalized laser engraving is produced in at least one screen printing layer which has previously been applied to a basic panel blank, the engraving consisting in material removal so as to form decorative features, icons, or similar signs in the screen printing layer, and then these engravings are covered by manually or automatically applying a layer of different color, which may be effected immediately after the engraving step or in a separate operation. Again, in this example, a plurality of layers are applied, and the laser engraving is performed between the coating steps. However, in terms of workflow it would be desirable to combine the coating process steps.